Unit Weight vs Sat Unit Weight in the CERM Sample Exam

[jaybird22]

If I'm given a retaining wall problem that gives the sat unit weight of the soil behind the wall, would I assume that it's below the water table and use the bouyant unit weight in calculating the vertical soil pressure?

This particular problem is in the CERM sample exam and the solution just uses the sat unit weight to find the vert soil pressure. I've been working under the assumption that if it's a sat unit weight then it's implicility below the water table. Why wouldn't they just give the wet unit weight or for that matter the unit weight if it's not below the water table?

Any assist would be appreciated! Thanks!

 

[Badger]

If I'm given a retaining wall problem that gives the sat unit weight of the soil behind the wall, would I assume that it's below the water table and use the bouyant unit weight in calculating the vertical soil pressure?
This particular problem is in the CERM sample exam and the solution just uses the sat unit weight to find the vert soil pressure. I've been working under the assumption that if it's a sat unit weight then it's implicility below the water table. Why wouldn't they just give the wet unit weight or for that matter the unit weight if it's not below the water table?

Any assist would be appreciated! Thanks!

Is this the 2008 sample exam, and if so which problem number in the sample exam?

 

[jamie]

a soil can be saturated and not be below the water table. unless they explicitly state where the water table is, I would not assume that it's there.

 

[EM_PS]

If I'm given a retaining wall problem that gives the sat unit weight of the soil behind the wall, would I assume that it's below the water table and use the bouyant unit weight in calculating the vertical soil pressure?
I've been working under the assumption that if it's a sat unit weight then it's implicility below the water table. Why wouldn't they just give the wet unit weight or for that matter the unit weight if it's not below the water table?

a soil can be saturated and not be below the water table. unless they explicitly state where the water table is, I would not assume that it's there.

Agreed! Don't never ever never ASSUME! Quests are worded to be tricky if you overthink them. Go with what the quest provides you - only use bouyant force specifically within the water table if one is present / given.

 

[jamie]

think about it this way - if you stick the corner of a paper towel in water, just about the whole thing will become saturated, but it won't be below the water line. soil can act in the same manner. saturated just means all the voids are filled with water, it doesn't mean there's free standing water in it. they have to tell you where the free water surface is.